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A step-by-step control and flooding process for low-permeability reservoirs

A low-permeability, oil-reservoir technology, applied in wellbore/well components, production fluids, sealing/packing, etc., can solve the problems of small radius, unsatisfactory water control and oil-increasing effect, short validity period, etc., and achieve small particle size. , Good swelling, good water swelling performance

Active Publication Date: 2020-08-07
PETROCHINA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problems of low-permeability reservoir conventional profile control and flooding with small radius, short effective period, and unsatisfactory effect of water control and oil increase, the present invention provides a step-by-step process for low-permeability reservoir control and flooding

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A step-by-step profile control and flooding process for low-permeability reservoirs, including the following five slug stages, including:

[0026] The first plug is a front plug, and the polymer solution is injected, and the volume percentage of the injection amount to the total injection amount is 4% to 6%;

[0027] The second slug is a plugging slug in the middle and high permeability zone of the transition zone, and the organic weak gel solution is injected, and the volume percentage of the injection amount to the total injection amount is 25%-30%;

[0028] The third slug is a high-permeability seepage channel blocking slug in the near-well zone, and the swelling particle suspension is injected. The injection volume accounts for 20%-25% of the injection volume;

[0029] The fourth slug is a deep plugging and flood control slug in the reservoir, and the volume percentage of the injected nano-polymer microsphere solution in the total injection volume is 30%-35%;

[0030] The fif...

Embodiment 2

[0033] On the basis of Example 1, the polymer solution contains 0.2% by mass polyacrylamide and 99.8% water; wherein the polyacrylamide is an anionic partially hydrolyzed polyacrylamide with a number average molecular weight of 1700 10,000 to 21 million, degree of hydrolysis 20% to 25%, solid content ≥89%.

[0034] The polymer solution is used as a pre-slug to pre-treat the oil reservoir, reduce the adsorption of polyacrylamide in the subsequent slug, and protect the gel forming performance of the subsequent injection of the organic weak gel.

Embodiment 3

[0036] On the basis of Example 1, the organic weak gel solution, by mass percentage, contains 0.2% to 0.3% polyacrylamide, 0.2% to 0.3% formaldehyde solution, and 0.025% to 0.03% isophthalic acid. Phenol, 0.03%~0.05% ammonium chloride, the rest is water; wherein the polyacrylamide is anionic partially hydrolyzed polyacrylamide, with a number average molecular weight of 17 million to 21 million, a degree of hydrolysis of 20% to 25%, and a solid content ≥89%; the formaldehyde solution is industrial formaldehyde with a mass percentage of 37%.

[0037] The organic weak gel solution injected by the second slug migrates to the transition zone and is used to block the medium and high permeability bands.

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Abstract

The invention provides a technology for low permeability reservoir gradual profile controlling and flooding. Profile controlling and flooding agents of different intensity are injected into five slugsin sequence, wherein a first slug is the front slug, and polymer solutions which account for 4%-6% of the total injection volume are injected; a second slug is a transition zone middle and high permeability zone plugging slug, and organic weak gel solutions which account for 25%-30% of the total injection volume are injected; a third slug is a hypertonic percolation channel plugging slug near a well, and bulk granular suspensions which account for 20%-25% of the total injection volume are injected; a fourth slug is a deep reservoir plugging and profile controlling and flooding slug, and nanopolymer microsphere solutions which account for 30%-35% the total injection volume are injected; and a fifth slug is an oil washing slug, and active water solutions which account for 10%-15% of the total injection volume are injected. According to the profile controlling and flooding technology, the technical requirements of the low permeability reservoir profile controlling and flooding that theinjection can be carried out, the plugging can be carried out and the flooding can be carried out are met, the gradual deep plugging and the profile controlling and flooding are realized, and the efficiency of water flooding oil washing and the reservoir recovery ratio are improved.

Description

Technical field [0001] The invention belongs to the technical field of profile control of water injection wells in oil fields, and specifically relates to a step-by-step control and displacement process for low-permeability oil reservoirs. Background technique [0002] Low-permeability oil fields have the characteristics of "low permeability, low pressure, and low abundance", and it is difficult to establish an effective displacement system. The method of "fracturing production + water injection development" is generally adopted for exploitation. Natural micro-fractures, artificial fracturing and The high-permeability channels formed by long-term water flooding and uneven water absorption in the profile of the injection wells caused the main oil well to inject water too quickly, prematurely flooded, and the lateral oil wells were difficult to achieve effective water injection. The reservoir water injection development effect was not ideal, and the lateral remaining Oil enrichment...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/22E21B33/13
CPCE21B33/13E21B43/16
Inventor 薛芳芳李宪文杨海恩何治武郑力军徐春梅张荣吴天江易萍刘保彻程辰陈荣环曹荣荣贾玉琴周广卿张涛
Owner PETROCHINA CO LTD
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